Use of Low Impact Development Systems to Enhance Recharge using Stormwater in a Heavily Groundwater-Depleted Region of the Gulf Coast Aquifer

Saheli Majumdar, Gretchen Miller

Water resources in the Houston Metropolitan Area, otherwise known as Greater Houston, have been under enormous stress for decades due to an increase in population and uncertain climate conditions. Rapid urbanization has also increased impervious cover, leading to excess stormwater runoff. Implementing managed aquifer recharge (MAR) through the use of low impact development (LID) strategies can augment stormwater infiltration and help replenish groundwater resources in the region. However, research on the effects of LID practices on groundwater quantity and quality in the Greater Houston metropolitan area is limited. The main objective of this study was to evaluate and compare the impact of two LID systems and the native soil on groundwater recharge and chemistry. Three test cells representing native soil, soil amendment, and trench aggregates were constructed in a detention basin in a Houston suburb and their performance was evaluated over a two-year period. We found that trench aggregates recorded the highest mean cumulative infiltration over the monitoring period, 1.5 times that of the soil amendment and 1.6 times that of the native soil. When the test cells were completely inundated, native soil registered a drainage of 773 mm which was 13 times that of trenches and 20 times that of soil amendment. The results from the infiltration data were supported by the groundwater elevation data. The groundwater quality was not highly affected during this study except for its salinity content. The findings suggest that retrofitting detention basins with LID systems helped enhance recharge over the long term. Native soil also facilitated significant infiltration when the detention basin was completely inundated for a prolonged period by modifying its outfall structure. The results from this study can help engineers better design existing stormwater detention basins to augment groundwater resources.